package com.abel.demo.thread;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;

@Slf4j
@Configuration
@EnableAsync
public class MyThreadPoolConfig {

    @Value("${async.executor.thread.core_pool_size}")
    private int corePoolSize;
    @Value("${async.executor.thread.max_pool_size}")
    private int maxPoolSize;
    @Value("${async.executor.thread.queue_capacity}")
    private int queueCapacity;
    @Value("${async.executor.thread.name_prefix}")
    private String namePrefix;

    @Bean(name = "asyncExecutor")
    public Executor asyncExecutor() {
        log.info("start asyncExecutor");
//        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        ThreadPoolTaskExecutor executor = new VisiableThreadPoolTaskExecutor();
        // 核心线程数：线程池创建时候初始化的线程数，超过该线程数后会进入任务队列
        executor.setCorePoolSize(corePoolSize);
        //配置最大线程数：线程池最大的线程数，只有在缓冲队列满了之后才会申请超过核心线程数的线程
        executor.setMaxPoolSize(maxPoolSize);
        //配置队列大小：用来缓冲执行任务的队列
        executor.setQueueCapacity(queueCapacity);
        // 允许线程的空闲时间60秒：当超过了核心线程之外的线程在空闲时间到达之后会被销毁
        executor.setKeepAliveSeconds(60);
        //配置线程池中的线程的名称前缀
        executor.setThreadNamePrefix(namePrefix);

        // 缓冲队列满了之后的拒绝策略：
        //CallerRunsPolicy()：交由调用方线程运行，比如 main 线程。
        //AbortPolicy()：直接抛出异常。
        //DiscardPolicy()：直接丢弃。
        //DiscardOldestPolicy()：丢弃队列中最老的任务。
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        //执行初始化
        executor.initialize();
        return executor;
    }
}
